Sadiq, Nadeem, et al. “TRANSCATHETER DEVICE CLOSURE OF SECUNDUM ATRIAL SEPTAL DEFECT (ASD) IN YOUNG CHILDREN: Atrial Septal Defect (ASD)”. Pakistan Armed Forces Medical Journal, vol. 64, no. 2, June 2014, pp. 355-59, https://pafmj.org/PAFMJ/article/view/878.